It's not that the venue is small, it's just that Ohio Melee tournaments have been skyrocketing in attendance for the past few months, which limits space.
I encourage you to keep playing Smash 64 because that game is awesome, but the fact of the matter is that the scene for that game is tiny.
Therefore, I encourage you also to pick up Melee. It's ridiculously fun, it has the biggest scene of all the smash games, and it just keeps growing and growing. Also, you'll have a much easier time finding people near where you live to play Melee with rather than Smash 64. I know it's difficult to get the hang of at first (I kept trying, failing, and going back to Brawl in the beginning, haha), but once you get the hang of it you'll love it.